Stainless Steel 316 Capillary Tubing Manufacturer & Supplier
Whether for high-pressure fluid systems, chromatograph laboratories, or marine controls, small dimensional errors can lead to big problems. If the microbore has a rough internal surface or wall thickness deviations in millimeters, it can affect flow rates, cause leakages, or hamper readings from sensors. At the mill in Mumbai, we produce a range of tubing made from micro-bores following the technical specifications so that our customers enjoy a dysfunction-free run of their operations.
We operate as a direct SS 316 capillary tube manufacturer and a dedicated stainless steel 316 capillary tubing supplier. We cold draw seamless SS 316 capillary tubing to handle high fluid pressures, severe chemical exposure, and elevated heat. Whether you need straight lengths cut clean and deburred or long continuous spools to cut down on extra fittings, our team handles cold drawing, bright annealing, trimming, and testing in-house.
If you are setting up larger instrumentation systems, check out our full range of SS 316 Pipes and Tubes for complete system integration.
Technical Data
Precision Technical Specifications & Manufacturing Standards
Every precision job brings distinct pressure, temperature, and material demands. Molybdenum in Grade 316 provides the pitting resistance needed for marine gear, chemical skids, and medical devices. We stock high grade mother hollows so we can start cold drawing your custom sizes right away.
| Parameter | Standard Specification |
|---|---|
| Outer Diameter (OD) | 0.30 mm up to 5.00 mm (0.012 inch to 0.200 inch) |
| Wall Thickness (WT) | 0.08 mm up to 1.00 mm (0.003 inch to 0.040 inch) |
| Inner Diameter (ID) | Custom micro bore dimensions down to 0.10 mm with tight tolerances |
| Dimensional Tolerances | OD and ID within plus or minus 0.02 mm |
| Supply Formats | Cut straight lengths up to 6 meters or continuous spools up to 500 meters |
| Surface Finish | Bright annealed, acid pickled, or electro-polished |
| Inner Surface Roughness | Ra less than or equal to 0.4 micrometers for smooth fluid passage |
| Manufacturing Standards | ASTM A269 Seamless Tubes and ASTM A213 Seamless Tubes |
Chemical Composition & Mechanical Properties
The addition of molybdenum in AISI 316 stainless steel gives superior resistance to chloride pitting and crevice corrosion compared to basic 304 grades.
| Element | Minimum Percent (%) | Maximum Percent (%) |
|---|---|---|
| Chromium (Cr) | 16.0 | 18.0 |
| Nickel (Ni) | 10.0 | 14.0 |
| Molybdenum (Mo) | 2.0 | 3.0 |
| Carbon (C) | 0.000 | 0.080 |
| Manganese (Mn) | 0.00 | 2.00 |
| Silicon (Si) | 0.00 | 0.75 |
| Phosphorus (P) | 0.000 | 0.045 |
| Sulfur (S) | 0.000 | 0.030 |
| Iron (Fe) | Balance | Balance |
Mechanical & Physical Properties
- Tensile Strength: 515 MPa minimum (75,000 PSI)
- Yield Strength (0.2% Offset): 205 MPa minimum (30,000 PSI)
- Elongation in 2 Inches: 35 percent minimum
- Hardness: 90 HRB maximum
Standard 316 SS Capillary Pipe Dimensions & Size Matrix
The table below lists standard precision sizes used across instrumentation, medical, and control applications. Custom inner and outer diameter combinations can be drawn upon request.
| Outer Diameter (OD) | Wall Thickness (WT) | Inner Diameter (ID) | Tolerance (OD/ID) | Standard Length Options |
|---|---|---|---|---|
| 0.50 mm | 0.10 mm | 0.30 mm | plus or minus 0.015 mm | Coiled or 2-meter straight |
| 1.00 mm | 0.20 mm | 0.60 mm | plus or minus 0.020 mm | Coiled or 3-meter straight |
| 1.50 mm | 0.25 mm | 1.00 mm | plus or minus 0.020 mm | Coiled or 3-meter straight |
| 2.00 mm | 0.30 mm | 1.40 mm | plus or minus 0.020 mm | Coiled or 6-meter straight |
| 3.00 mm | 0.50 mm | 2.00 mm | plus or minus 0.025 mm | Coiled or 6-meter straight |
| 4.00 mm | 0.80 mm | 2.40 mm | plus or minus 0.030 mm | Coiled or 6-meter straight |
| 5.00 mm | 1.00 mm | 3.00 mm | plus or minus 0.030 mm | Coiled or 6-meter straight |
Pressure Rating Reference Chart
Capillary tubing handles high interior pressures due to its small outer diameter and heavy wall ratio. The table below lists estimated working pressure and theoretical burst pressure calculated per ASME B31.3 standards at room temperature.
| Outer Diameter | Wall Thickness | Estimated Working Pressure | Estimated Burst Pressure |
|---|---|---|---|
| 1.00 mm | 0.20 mm | 4,200 PSI (290 Bar) | 16,800 PSI (1,160 Bar) |
| 1.50 mm | 0.25 mm | 3,500 PSI (241 Bar) | 14,000 PSI (965 Bar) |
| 2.00 mm | 0.30 mm | 3,100 PSI (213 Bar) | 12,400 PSI (855 Bar) |
| 3.00 mm | 0.50 mm | 3,600 PSI (248 Bar) | 14,400 PSI (992 Bar) |
| 4.00 mm | 0.80 mm | 4,400 PSI (303 Bar) | 17,600 PSI (1,213 Bar) |
Grade 316 vs Grade 316L Capillary Tubing
Selecting between standard Grade 316 and low carbon Grade 316L depends on your thermal exposure and fabrication methods.
| Feature | SS 316 Capillary Tubing | SS 316L Capillary Tubing |
|---|---|---|
| Carbon Content | Maximum 0.08 percent | Maximum 0.03 percent |
| Mechanical Strength | Slightly higher tensile and yield strength | Slightly lower strength than standard 316 |
| Welding Suitability | Risk of carbide precipitation during heavy welding | Excellent resistance to intergranular corrosion after welding |
| Operating Temp | Up to 800 degrees Celsius in non-welded setups | Up to 450 degrees Celsius for welded assemblies |
| Typical Usage | Machined probes, sensors, and structural micro lines | Welded manifolds and medical assemblies |
For applications requiring low-carbon material to prevent heat-affected corrosion, view our SS 316L Pipes & Tubing.
Key Industrial Applications
Precision SS 316 micro tubes perform critical roles in systems where fluid flow must be metered down to microliters per minute:
- High Performance Liquid Chromatography (HPLC): Precision micro bore tubes deliver smooth solvent flow without sample cross-contamination.
- Medical Probes & Surgical Tools: Used for liquid dosing needles, sample collection probes, and endoscopic equipment.
- Pressure Transmitters & Impulse Lines: Transmits pressure signals accurately to remote sensors while dampening pressure surges.
- HVAC Expansion Valves: Acts as a metering device for refrigerant expansion in commercial cooling circuits.
- Offshore & Marine Instrumentation: Resists marine atmosphere pitting in hydraulic control lines on rigs and naval vessels.
To learn more about how small diameter components function under severe conditions, read our guide on Industrial Applications Guide.
Testing & Quality Assurance
A minor inner wall defect or burr can disrupt fluid delivery or distort sensor metrics. Every production run undergoes rigorous checking before shipment:
- Hydrostatic and Air Under Water Tests: Every length is pressurized to catch micro leaks or wall porosity.
- Eddy Current Inspection: Scans the full tube length to verify internal metal structure uniformity.
- Microscopic Roughness Inspection: Inner bore Ra values are verified with optical equipment to ensure smooth flow.
- Flaring and Flattening Tests: Samples are expanded and compressed to confirm ductility for bending and swaging.
- PMI Chemical Verification: Handheld analyzers confirm exact alloy ratios on every heat lot.
Complete System Accessories
To build reliable microfluidic assemblies, precision tubing must connect seamlessly to larger headers, manifolds, and valves. We manufacture matching Stainless Steel 316 Forged Fittings designed to interface with precision instrumentation lines.
Frequently Asked Questions
What is the advantage of bright annealing for capillary tubing?
Bright annealing processes the tubes in a sealed hydrogen furnace atmosphere. This prevents oxygen scale buildup, keeping both the inner and outer surfaces smooth, bright, and clean without requiring secondary acid pickling.
What is the minimum inner diameter available in SS 316?
We routinely cold draw inner diameters down to 0.10 mm with tight tolerances, making them suitable for chromatography columns and fine fluid injection systems.
How is delicate capillary tubing protected during transit?
Straight lengths are packed into thick PVC sleeves or lined wooden cases with internal end blocks. Coiled lengths are wrapped in heavy protective plastic sheeting and crated to prevent crushed ends or kinks.
Request a Custom Quote
Looking for a reliable SS 316 capillary tube manufacturer or a trusted stainless steel 316 capillary tubing supplier? Send your dimensions, wall tolerances, and volume requirements to our sales engineering desk.
- Email: sales@amardeepsteel.com
- Phone: +91 22 67439130 / +91 22 67439165
- Factory Address: Sanghrajka House, 2nd Floor, Office No 10, Opera House, Mumbai 400004, Maharashtra, India
